1. Field of the Invention
The present invention relates to an illumination apparatus to be attached to an image pickup apparatus including a light-emitting portion for applying illumination light to outside, and an image pickup system including the illumination apparatus.
2. Description of Related Art
Conventionally, image pickup apparatuses having an image pickup function have been put into practical use, in which a light-emitting portion is integrally incorporated in the apparatus main body, for applying illumination light to an external object in order to obtain sufficient exposure amount when image pickup operation is performed under a low brightness environment such as night or shade, for example.
As the light-emitting portion provided in such a conventional type of image pickup apparatus, a light-emitting portion including, as a light source thereof, for example, a flashing light-emitting device using a flash discharge tube, and also including a light-emitting diode (LED) as another light source has been put into practical use.
In the case where an image pickup operation is performed with the above-described light-emitting portion by using the image pickup apparatus of such a conventional type, at the time of, what is called, a proximate image pickup in which an object as an image pickup object, in particular, is located in an extremely close area (for example, located in close range in which the distance to the object is several centimeters), there is a case where a desired object is not appropriately irradiated with the illumination light applied from the light-emitting portion. Specifically, the illumination light sometimes cannot be evenly applied to the desired object due to a structure such as a lens barrel provided on the front surface side (object side) of the image pickup apparatus interfering with the illumination light from the light-emitting portion, for example. In such a case, light amount insufficiency partly occurs in the image to be obtained.
Therefore, in recent years, Japanese Patent Application Laid-Open Publications Nos. 2005-258011, 2014-142564, and 2009-237298, for example, disclose various kinds of illumination adapters, which are illumination apparatuses as accessory apparatuses, configured to be attached to an image pickup apparatus including a light-emitting portion, to guide illumination light, which is applied from the light-emitting portion of the image pickup apparatus to outside, to the vicinity of an image pickup optical system and obtain diffused illumination light, to thereby be capable of obtaining the illumination light to be evenly applied to an object also at the time of proximate image pickup.
The illumination apparatus disclosed in each of the Japanese Patent Application Laid-Open Publications Nos. 2005-258011, 2014-142564, etc., is an illumination apparatus configured to be attached to an image pickup apparatus including a light-emitting portion using a light-emitting diode as a light source.
In addition, the illumination apparatus disclosed in the Japanese Patent Application Laid-Open Publication No. 2009-237298 is an illumination apparatus to be used by being attached to the image pickup apparatus including a flashing light-emitting device using a flash discharge tube as a light source of the light-emitting portion.